Counterweighted lift trucks are widely used in industry, e.g. forklift trucks and other elevated platforms. FIG. 1 illustrates, in perspective view, a typical forklift truck 1 that may be used to move pallets in a warehouse environment. The forklift truck has a fork arrangement 2 at the front of the truck to engage with a pallet to be lifted and a lifting mechanism 3 to enable the forks to be raised and lowered as required. In order to prevent the truck from toppling over when carrying a load on the forks, a counterbalance weight 4 is provided at the rear of the vehicle. Such counterbalance weights are often styled to resemble body panels, but in fact consist of a large block of dense material, such as cast iron. In many forklift truck systems, these counterweights may weigh anything up to 1-1.5 tonnes. In many such systems, and in order to further increase the counterbalance effect, the engine for the vehicle is located within a cavity behind the counterweight 4. In effect, the counterweight 4 is generally concave in construction, with the engine sitting partially within the envelope created by the counterweight.
For forklift trucks that use internal combustion engines, exhaust from the engine must be vented to atmosphere. Because such forklift trucks are often used in a confined environment, it is often necessary that the exhaust tail pipe 5 vents at a relatively high level on the vehicle. As a result, it is often required that the tail pipe 5 passes through the counterweight 4. Such vehicles are often used in cramped environments, and it is common that the tailpipe 5 becomes damaged—especially when located in an elevated position—and needs to be replaced. This requires that the coupling between the exhaust tail pipe and the rest of the exhaust system is dismantled and reassembled to allow replacement. Due to the large mass of the counterweight 4, it is not feasible to remove the counterweight to gain access to the engine compartment. As a result, the counterweights are often provided with access holes 6 through which limited access may be granted to the engine compartment and the exhaust coupling.
FIGS. 2-4 illustrate typical exhaust couplings used in the industry. FIG. 2 shows an arrangement in which two sections of exhaust pipe 7, 8 may be joined by providing a slightly larger diameter end to one of the pipes 8, for example by flaring the end of the pipe, and by providing a slit 9 extending a short way along the axis of the pipe. In this way, one pipe 7 may be inserted into the end of the other pipe 8 and the two pipes clamped together by means of a circular clip (not illustrated).
FIG. 3 illustrates another common alternative configuration, in cross-sectional view. In this system, the two pipes 7, 8 are provided with a flared or flanged end and the pipes are abutted against each other with an interposing sealing ring or gasket 10. Once assembled in this configuration, the pipes and gasket are held together by a circular clip 11 surrounding the assembly. Such a clip 11 is shown in plan view in FIG. 4 comprising two arcuate portions 12, 13 connected at each end by fasteners 14 usually comprising a screw arrangement.
It will be appreciated that assembling and disassembling such couplings within the confined environment of the engine compartment such as a lift truck, where access is only available through small access holes 6 is extremely difficult. Dexterity is required to manipulate the exhaust pipe couplings, which is ideally a two-handed operation, although the small access holes rarely allow both hands to be inserted into the engine compartment. As a result, significant downtime is often experienced when tail pipes need to be changed on lift trucks, thereby leading to operational difficulties and lost working time.
It is amongst the objects of the present invention to provide a solution to this and other problems. It will be appreciated that the solutions proposed are equally applicable to situations where exhaust pipes need to pass through armour plating, for example on military vehicles.